Bennett patent U.S. Pat. No. 3,482,447, Glab et al U.S. Pat. No. 5,649,450, and Webb U.S. Pat. No. 5,144,836 all disclose liquid level sensing gauges for use with storage tanks for liquid fuels and the like. The gauge assemblies include, in each case, a gauge housing designed to be mounted at a top opening of a liquid storage tank. Within the housing is a spring-biased spool upon which a filament is wound. The end of the filament extends into the tank through its opening and is connected to a float member that floats on the surface of the liquid. Indicator means mounted on the housing or associated therewith is calibrated to reveal the liquid level in the tank by means of the extent to which the filament has been unwound from the spool. In all patents, the floats are too large to pass upwardly through the tank openings into the housings of the gauge assemblies, and in the Webb and Glab et al patents clip means are provided at the ends of the filaments to act as stop elements to prevent the filaments from retracting completely into the housings even when the clips are unattached to floats.
A main advantage of providing a housing with a lower opening that is too small to allow an adapter clip to be pulled by the filament upwardly into the housing is that the gauge may be shipped and connected by the user to other components without fear that the filament will be drawn completely into the housing before a float is attached to the clip. Such an arrangement also has its disadvantages, however. It is possible during shipment that the constant force exerted by the spring on the spool is insufficient to keep the filament in wound condition on the spool. A more likely possibility is that at the time of installation a user might pull on the clip to withdraw a portion of the filament and then intentionally or unintentionally release the clip, causing retraction of the filament by reason of the constant-force spring acting on the spool. If the pulling and releasing actions are performed quickly, faster than can be accommodated by the inertia of the spool, one or more windings of filament may come off the spool and jam the gauge mechanism. Untangling the filament within the housing is a job that is usually beyond the capabilities of the user or installer, with the result that a disconcertingly high number of gauge assemblies must be returned to the manufacturer for disassembly, correction, and reassembly of such gauges.
Accordingly, a main aspect of this invention lies in providing a gauge assembly with spool locking means that eliminates or greatly reduces the possibility of a filament coming unlooped from a spool and tangled within a housing during shipment, storage and/or handling prior to installation and at the time of installation. More specifically, it is an object of this invention to provide an assembly in which the free end of the filament, although exposed for attachment to a float at the time of assembly, cannot be pulled to rotate the spool to cause a xe2x80x9cyo-yoxe2x80x9d action of the spool until locking means are removed from the interior of the housing.
The locking means takes the form of at least one strip of a removable adhesive tape having opposite end portions adhering to the housing and having a central portion adhering to an end wall of the spool. The tape therefore locks the spool against rotation until such time as the tape is peeled away from the housing and spool. Because the tape is relatively wide, it provides a substantial surface on which warning indicia and appropriate instructions may be imprinted. Therefore, during handling and installation, purchasers and installers may be clearly informed as to the purpose of the tape and the procedures and timing for its removal.
The housing for the gauge assembly has an access opening for exposing the spool and a removable cover that extends over that access opening. The central portion of the tape contacts and immobilizes the spool within the housing and the cover must therefore be detached before the locking tape can be removed.
The locking means may also include a second strip of adhesive tape detachably securing the otherwise free end of the filament to the housing (the housing includes the threaded tubular neck for attaching the gauge assembly to a liquid storage tank). In addition, removable resilient means may be provided within the housing for engaging and holding the filament upon the spool. Such resilient means may take the form of a compressible foam wedge element disposed within the housing and compressibly engaging both the filament wound upon the spool and an adjacent wall surface of the housing. Such foam wedge element is easily removed from the housing through the access opening at the time of installation.